<!DOCTYPE html>
<html>
  <head>
        <meta charset="utf-8">
        <title>testD3-32-ArrowForce.html</title>
        <script type="text/javascript" src="d3.v3.js"></script>
    <style type="text/css">
path.link {
  fill: none;
  stroke: #666;
  stroke-width: 1.5px;
}

marker#licensing {
  fill: green;
}

path.link.licensing {
  stroke: green;
}

path.link.resolved {
  stroke-dasharray: 0,2 1;
}

circle {
  fill: #ccc;
  stroke: #333;
  stroke-width: 1.5px;
}

text {
  font: 10px sans-serif;
  pointer-events: none;
}

text.shadow {
  stroke: #fff;
  stroke-width: 3px;
  stroke-opacity: .8;
}
}

</style>
    </head>
    <body>
    <p>力导向图之弧形箭头连线</p>
        <script type="text/javascript">
var links = [
  {source: "Microsoft", target: "Amazon", type: "licensing"},
  {source: "Microsoft", target: "HTC", type: "licensing"},
  {source: "Samsung", target: "Apple", type: "suit"},
  {source: "Motorola", target: "Apple", type: "suit"},
  {source: "Nokia", target: "Apple", type: "resolved"},
  {source: "HTC", target: "Apple", type: "suit"},
  {source: "Kodak", target: "Apple", type: "suit"},
  {source: "Microsoft", target: "Barnes & Noble", type: "suit"},
  {source: "Microsoft", target: "Foxconn", type: "suit"},
  {source: "Oracle", target: "Google", type: "suit"},
  {source: "Apple", target: "HTC", type: "suit"},
  {source: "Microsoft", target: "Inventec", type: "suit"},
  {source: "Samsung", target: "Kodak", type: "resolved"},
  {source: "LG", target: "Kodak", type: "resolved"},
  {source: "RIM", target: "Kodak", type: "suit"},
  {source: "Sony", target: "LG", type: "suit"},
  {source: "Kodak", target: "LG", type: "resolved"},
  {source: "Apple", target: "Nokia", type: "resolved"},
  {source: "Qualcomm", target: "Nokia", type: "resolved"},
  {source: "Apple", target: "Motorola", type: "suit"},
  {source: "Microsoft", target: "Motorola", type: "suit"},
  {source: "Motorola", target: "Microsoft", type: "suit"},
  {source: "Huawei", target: "ZTE", type: "suit"},
  {source: "Ericsson", target: "ZTE", type: "suit"},
  {source: "Kodak", target: "Samsung", type: "resolved"},
  {source: "Apple", target: "Samsung", type: "suit"},
  {source: "Kodak", target: "RIM", type: "suit"},
  {source: "Nokia", target: "Qualcomm", type: "suit"}
];

var nodes = {};

links.forEach(function(link) {
  link.source = nodes[link.source] || (nodes[link.source] = {name: link.source});
  link.target = nodes[link.target] || (nodes[link.target] = {name: link.target});
});

var w = 960,
    h = 500;

var force = d3.layout.force()
    .nodes(d3.values(nodes))
    .links(links)
    .size([w, h])
    .linkDistance(60)
    .charge(-300)
    .on("tick", tick)
    .start();

var svg = d3.select("body").append("svg:svg")
    .attr("width", w)
    .attr("height", h);

//(1)创建箭头
svg.append("svg:defs").selectAll("marker")
    .data(["suit", "licensing", "resolved"])
  .enter().append("svg:marker")
    .attr("id", String)
    .attr("viewBox", "0 -5 10 10")
    .attr("refX", 15)
    .attr("refY", -1.5)
    .attr("markerWidth", 6)
    .attr("markerHeight", 6)
    .attr("orient", "auto")
  .append("svg:path")
    .attr("d", "M0,-5L10,0L0,5");
//(2)根据连线类型引用上面创建的标记
var path = svg.append("svg:g").selectAll("path")
    .data(force.links())
  .enter().append("svg:path")
    .attr("class", function(d) { return "link " + d.type; })
    .attr("marker-end", function(d) { return "url(#" + d.type + ")"; });

var circle = svg.append("svg:g").selectAll("circle")
    .data(force.nodes())
  .enter().append("svg:circle")
    .attr("r", 6)
    .call(force.drag);

var text = svg.append("svg:g").selectAll("g")
    .data(force.nodes())
  .enter().append("svg:g");

// A copy of the text with a thick white stroke for legibility.
text.append("svg:text")
    .attr("x", 8)
    .attr("y", ".31em")
    .attr("class", "shadow")
    .text(function(d) { return d.name; });

text.append("svg:text")
    .attr("x", 8)
    .attr("y", ".31em")
    .text(function(d) { return d.name; });

// 使用椭圆弧路径段双向编码。
function tick() {
//(3)打点path格式是：Msource.x,source.yArr00,1target.x,target.y
  path.attr("d", function(d) {
    var dx = d.target.x - d.source.x,//增量
        dy = d.target.y - d.source.y,
        dr = Math.sqrt(dx * dx + dy * dy);
    return "M" + d.source.x + ","
    + d.source.y + "A" + dr + ","
    + dr + " 0 0,1 " + d.target.x + ","
    + d.target.y;
  });

  circle.attr("transform", function(d) {
    return "translate(" + d.x + "," + d.y + ")";
  });

  text.attr("transform", function(d) {
    return "translate(" + d.x + "," + d.y + ")";
  });
}
        </script>

    </body>
</html>
